Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a porcentagem para quando contra a proibição é 2978?
 ###Tabelas: CREATE TABLE completed_buildings (completed_buildings_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Building VARCHAR, City VARCHAR, Height (m/ft) VARCHAR, Built INT) CREATE TABLE season_5_1992 (season_5_1992_id AUTO_INCREMENT PRIMARY KEY, Number in series INT, Number in season INT, Title VARCHAR, Directed by VARCHAR, Original air date VARCHAR, Production code VARCHAR) CREATE TABLE complete_world_championship_grand_prix_results (complete_world_championship_grand_prix_results_id AUTO_INCREMENT PRIMARY KEY, Year INT, Entrant VARCHAR, Chassis VARCHAR, Engine VARCHAR, Points INT) CREATE TABLE referendum_on_prohibition (referendum_on_prohibition_id AUTO_INCREMENT PRIMARY KEY, Jurisdiction VARCHAR, For Prohibition INT, Percent For VARCHAR, Against Prohibition INT, Percent Against VARCHAR) CREATE TABLE tennessee_counties_ranked_by_per_capita_income (tennessee_counties_ranked_by_per_capita_income_id AUTO_INCREMENT PRIMARY KEY, County VARCHAR, Per capita income VARCHAR, Median household income VARCHAR, Median family income VARCHAR, Population INT, Number of households INT)  
SELECT Percent For FROM referendum_on_prohibition WHERE Against Prohibition = 2978